Carburizing box



E 'mi INVENTORl Her'zr H. Harms BY y AT l @HNF-:vb1

l Patented 17, 1936.

UNITED 'sTATEs PATENT OFFICE 6 Claims.

This invention relates to carburizing boxes and is an improvement on the invention of my Patent No. 1,882,580.

It is an object'of my invention to provide a carburizing box which will standup better and longer Vunder the severe usage which such boxes receive.

specification.

' dling,

It is a further object'of my invention to provide a carburizing box which will have a longer service life in proportion to the diiculty and expense of making same.

Other objects will appear in the course of this When carburizing boxes are to he used in heat treating furnaces, metal articles to be carburized 'are placed in the boxes, together with a carburizing agent such as bone dust. Traysv are placed over the boxes, the boxes with their trays are then usually inverted, and in this position are s'ubjected in a heat'treating furnace to heat usually supplied from beneath. 4 The boxes must stand up under rough hanextremely high temperatures, sudden changes in temperature, and the pressure of a heavy load of contents while softened by heat, all with attendant warping and buckling, producing cracks and ultiniately finally breaking the box down.

As a result, if the boxes were not made Vso as.

to have great durability under such treatment they would have to be replaced constantly at great expense, and it becomes a problem of some nicety and importance to devise a box having the longest life in proportion to thecost of producing same, in which my invention which is illustrated in the drawing .herewith represents an advance over the art.

Insaid drawing, Fig. 1 is a plan view of a box constructed in accordance with my invention;

Fig. 2 is a section thereof taken on line 2-2 of Fig. 1; and

Fig. 3 is a detail section on line 3 3 of Fig. 1.

The box is made up of ve parts, one cross part l0, and four corner parts I2a, 12b, |20, and 12d.

The cross part I is made of a material more flexible under operating conditions and more cap able of absorbing strains without cracking or giving way. This material is preferably a sheet of high grade ductile heat resistant alloy, such as high nickel chromium alloy which is low in iron content.

The corner parts I2a, I2b, |2c, and I2d are preferably made of relatively inexpensive cast metal,l preferably' nlckel-chromi-um-iron alloy with high iron content. i

The cross part is formed with one or more corrugations running lengthwise of each of the four arms thereof. In the embodiment shown in the 5 drawing as illustrative of my invention, there are three corrugations in each arm. The front, inward corrugation of end arm a continues around and becomes the left, inward corrugation of front arm 10d; the right, inward corrugation 10 of front arm Id continues around and becomes the front, inward corrugation of right arm Ic; the back, inward corrugation of arm Illc continues around and becomes the right, inward corrugation of back arm lllb; the left, inward corrugation of arm Iilb continues around and becomes the back, inward corrugation of left The center corrugations of all the arms are outward and leadto the center of the floor of the box where they broaden and merge. Preferably at the center where the axes meet I provide a Vcircular raised mound 20, the purpose of which will appear hereinafter.

It will be obvious that the edge corrugations could be downward and the center ones upward, and that various numbers of corrugations other than three could be provided. In fact, a single corrugation to each arm could be used instead of the three shown. Furthermore, the central area where the center corrugations merge could be given a shape other than the one shown. 'The form shown is, however, preferred because while relatively simple it gives great flexing and absorbing of strains.

The four corner parts are each three sided, each forming part of the floor, an end wall, and a side wall of the carburizing box. These corner parts are secured to the cross part preferably by being cast around the edges of the cross part with 40 fork flanges I4, I6 embracing same. Holes I8 are formed in the cross part along the edges thereof, and when the corner parts are cast thereabout their fork portions are joined through the holes, securely anchoring the parts together.

Because the corner parts are open, with their sides extending at right angles to each other, casting thereof is facilitated, they can be cast thinner, and there will be fewer casting strains as in casting the metal does not have to flow so far and around such devious courses as would be the case in casting, for instance, an entire integral box.

In operation the relatively exible, heat resistant, strain absorbing material of the cross partisfreetoilexallthewayncrsalongeither wmntheenumboxbendninngoneaxmm' I claim: x 1. A metallic receptacle for use in heat treating furnaces comprising a cross part having four arms extending out along the bottom from their common center and then up the sides, four corner partssecuredtothecrossparttoformarectangular box, and a corrugation extending the full length of each pair of opposite arms, said corrugations merging at the crossing point.

2. nevxceofelsimlxhwmentnecmpmis formed of a more ilexibie metallic material than the corner parts.

3. Device of claim 1 in which the cross partis formed from a.A sheet of high grade relatively exibie heat resistant alloy and the corner parts are formed of relatively inexpensive cast metal.

.4. Device of cl in which the corrugations merge is generaliy planar and is distended into a' circular mound at Athe center. Y

5. Device of claim 1 in which the therein mentioned corrugation is centrally disposed and an oppositely curved corrugationtlanks it on each side, said iianking corrugations curving oi! near the center of the receptacle and following along the edges of the -corner parts.

6. A metallic receptacle tor use in heat treat-- 1 in which the common area.

ing furnaces comprising a four arm cross part oi high grade relatively iiexible heat resistant alloy, the crossing and the inner parts oi said arms being generally horizontal and the outer parts o1 the arms extending upward, corner parts formed o! relatively inexpensive cast metal secured to said arms and being so shaped as with the cross to i'orm a box, a plurality of lengthwise corrugations formed in each arm, a central one of said corrugations in each arm continuing and merging with the corresponding corrugation of the opposite arm, and the edge corrugation oi' each arm curving around the corner oi' the adjacent corner part and merging with the corresponding corrugation of the adjacent arm.

HENRY H. HARRIS. 

